Brake pedal goes to the floor
My brake pedal is still going to the floor. I have a 1992 Ford F250 4x4 diesel pickup truck, and I cannot get the pedal to stay firm. I have replaced all brake shoes and all brake pads, the master cylinder twice, the power brake booster once, and have bled it multiple times. I have also replaced both front brake hoses. I have currently using a vacuum system to bleed the brakes with. I have also used the method of two people, one pushing the pedal down with me opening the bleeder to let the fluid escape with any and all air hopefully. My next step is to manually bleed the brakes with someone pumping the brakes while I let fluid and air out of the bleeder screws. I have not noticed any leaking brake fluid from any of the hard lines that I can see. I did notice that the pedal does have a pulse feeling when it goes to the floor. I thought it might have something to do with the RABS system so I removed the 15 amp fuse and that stoped that. Is there anyone out there that can give me some idea of what I might be doing wrong? Please help if you can and thanks for reading and any suggestions.
Larry “Retired Coastie”

No magic solution for you, but I'm a little confused by your different methods of bleeding the brakes. What I have always done-- have someone in the cab pump the brake pedal until it is firm and HOLD. You under the truck, crack open the bleeder screw and let the fluid (and air) bleed out. When the guy in the cab gets the pedal to the floor you immediately close the bleeder. Repeat. That's how I've always done it.

BTW, I seem to recall a bleeder screw on the RABS unit on my 90, and I also recall the RABS units being problematic. Two other things to consider...

Thanks Adam, I have finished replacing every part of the brake system except the RABS valve. I have rebled the brakes using the method I found in the repair manual. I had my son-n-law press the brake pedel down while I opend the bleader and let fluid escape into a jar (via a clear tube) with clean brake fluid it until all of my bubbles were gone. I now have good brakes and only have to push down litely. This is a good thing. The problem is that the pedel is still going to the floor even with lite to moderate pressure. I wonder if my push rod on my power brake booster is to short. The installation sheet said to adjust it to line up flush with the flat surface of the booster. Does anyone have any ideas?

I bled the master cylinder by removing the attached lines and holding my fingers over the ports. I had someone push the pedel to the floor as I held my finger there. When the pedel hit the floor and air and fluid escaped, I held my finger tight as the pedel was let up. This action allows fresh fluid to refil the body of the master cylinder. I did this a minimum of 6 times each. After that I reconnected the lines and had my helper reapply pressure to the pedel again, I crached the rear brake line to allow any trapped air to escape again. I did the same thing for the front brakes. Also, I made sure the master cylinder was full at all times.

Did you ever figure out what the problem was? I am having a similar issue.Replaced almost everything except for ABS crap. I did notice several people talking about a Zero Loss Brake Booster that Ford made to replace the issue of soft brakes or brakes going to the floor. Where did you buy your Brake Booster. I put an aftermarket one on and still have issues. I did adjust the Brake booster rod which helped a little bit but than got soft again. Trying to get more info on the Ford booster. The brake booster part # is F5TZ2005CA. If anybody esle has heard of this part or used it can you please chime in. Found part but doesn't say anything about being different.

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